简介: |
讲座简介：
While the TOA broadband flux and cloud radiative effect (CRE) acquired from ERBE and CERES have been extensively used in climate study and GCM evaluations, the flux and CRE over each individual absorption band (termed as band-by-band flux and CRE) has its unique strength in GCM evaluation because (1) comparing band-by-band CRE and flux avoids the compensating biases in the broadband comparison and (2) the fractional contribution of each band to the LW broadband CRE (fCRE) is sensitive to the cloud top height but largely insensitive to the cloud fraction, presenting a unique diagnostic metric to separate the two macroscopic properties of clouds most relevant to longwave CRE.
A series of recent studies by my group that established algorithms of deriving spectral flux from AIRS observations in a way fully consistent with CERES radiance-to-flux algorithm will be first introduced. Next, a summary of findings in our studies of evaluating band-by-band clear-sky fluxes and CREs over the tropical oceans simulated by three different atmospheric GCMs (GFDL AM2, NASA GEOS-5, and Canadian CCCma CanAM4) will be given. Such comparisons quantitatively demonstrate the compensating errors originated from different bands as well as different spatial patterns of biases in different bands, which can be further attributed to underlying physical processes. The seasonal cycle and interannual variability of band-by-band CRE will also be depicted. If time allows, a recent study of comparing far-IR spectral flux derived in such way with those computed from three most recent reanalyses, ECMWF ERA-interim, NASA MERRA, and NCEP CFSR will be presented.
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